Antioxidants for oils and oil compositions containing the same



Patented July is, 1950 ANTIOXIDANTS FOR OILS AND OIL CONIPO- SITIONS CONTAINING THE SAME Donald R. Stevens, Wilkinsburg, and Arthur C.

Dubbs, Springdale, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application March 22, 1948, 7 Serial No. 16,394 M e Claims.

This invention relates to antioxidant fo oils and oil compositions containing the same, and more particularly, it relates to oil compositions containing the product resulting from the condensation of an alkyl phenol and furfural or an alkyl substituted furfural; all as more fully hereinafter set forth and as claimed.

Gasolines made by the thermal cracking of heavier petroleum oils, and gasolines made by the polymerization of normally gaseous hydrocarbons, contain certain undesirable constituents, for example, diolefins and cyclic oleflns, which are subject to oxidational changes with resultant formation of gums and color-imparting bodies. Unless these undesirable constituents are removed or unless their oxidation is inhibited, gasolines are obtained which tend to deposit gums and to discolor in storage and in handling.

Various methods have been employed for removing the undesirable constituents from gasolines such as washing with sulfuric acid or contacting with a solid adsorbent. These methods, however, have not been entirely satisfactory in that high treating losses are encountered and in many instances, gasolines are obtained which are not suificiently free from the undesirable gumforming constituents.

A large number of oxidation inhibitors have been developed for obviating the effects of the undesirable constituents, but many of these inhibitors are subject to the disadvantage that they are water soluble and soluble in dilute aqueous alkali solutions so that gasolines to which they have been added tend to be deprived of the antioxidant material upon contact with water or dilute aqueous alkali solutions.

In addition to gasolines, other petroleum oils such as lubricating oils, turbine oils, transformer oils, and the like, as well as animal and vegetable oils are also subject to undesirable oxidational changes in storage and in use, which result in definite deterioration of quality and character of these oils. For example, oxidation of petroleum lubricating oils results not only in the formation of compounds which are corrosive to metals, but also in the deposition of sludge in the crankcase and the formation of varnish and gum on the pistons and cylinder walls of internal combustion engines. Oxidation of animal and vegetable oils results in the development of rancidity of the oils.

It is, therefore, an object achieved by this invention to provide an improvement agent or when incorporated in an oil will substantially retard deterioration thereof.

It is a further object achieved by this invention to provide an oil composition containing a compound which will inhibit or substantially retard deterioration of the oil.

It is a still further object achieved by this invention to provide an oil composition containing wherein R is selected from the class consisting of furyl and" alkyl substituted furyl groups, R1 is a tertiary alkyl radical containing at east 4 carbon atoms, and R2 is a member of the group consisting of hydrogen and alkyl radicals containing no more than 8 carbon atoms. The R, R1 and R5 substituents are such that the compounds are insoluble in dilute aqueous, alkali solutions and water, while soluble in hydrocarbon oils and serve as antioxidants when incorporated therein. The following compounds are illustrative of the compounds which fall within the scope of our invention. It should be understood, however, that these compounds are given by way of example and that our invention is not limited to these compounds except as recited in the appended claims.

Bis(2-hydroxy-5-t-butylphenyl) -furylmethane; Bis(2-hydroxy-5-t-amylphenyl) -fury1methane; Bis (2-hydroxy-5-t-octylphenyl) -furylmethane; Bis(2-hydroxy-3-t-butylphenyl) -furylmethane; Bis(2-hydroxy-3-t-amylphenyl) -furylmethane; Bis(2-hydroxy-3-t-octylphenyl) -furylmethane; Bis(2 hydroxy 3,5 di t butylphenyl) -furylagents of the character indicated herein, which as methane;

Bis(2 hydroxy 3,5 di t-amylphenyl) -furylmethane;

Bis(2 hydroxy 3,5 di t-octyiphenyl) Jury]- methane;

Bis (2 hydroxy 3 tbutyl--sec-butylpheny1) iurylmethane;

' Bis(2 hydroxy 5 t-butyl-3-sec-butylphenyll Bis(2 hydroxy 5 isopropyl-Zi-t-octylphembfurylmethane; 1

Bis(2 hydroxy 3-ethyl-5-t-butylphenyl) -i'urylmethane;

Bis(2 hydroxy 3-ethyl-5-t-amylphenyl) -fury1- methane;

Bis(2 hydroxy 3-ethyl-5-t-octylphenyl) -furylmethane;

Bis(2 hydroxy 5-ethyl-3-t-butylphenyl) methane;

Bis(2 hydroxy 5-ethyl-3-t-amylpheny1)-furylmethane;

Bis(2 hydroxy 5-ethyl-3-t-octylphenyl) -iurylmethane;

Bis(2 methyl 4-hydroxy-5-t-butylphenyl) -i'urylmethane;

Bis(2 methyl 4-hydroxy-5-t-amylphenyl) -furylmethane;

Bis(2 methyl 4-hydroxy-5-t-octylphenyl)-i'urylmethane;

Bis(2 hydroxy 3-methy1-5-t-butylphenyl) -i'urylmethane;

Bis(2 hy('i oxy 3-methyl-5-t-amylphenyl) -iurylmethane;

Bis(2 hydroxy 3-methyl-5-t-octylphenyl)durylmethane;

Bis(2 hydroxy 3-t-butyl-5-methylphenyl) -iurylmethane;

Bis(2 hydroxy 3-t-amyl-5-methylphenyl) -furylmethane;

Bis(2 hydroxy 3-t-octyl-5-methy1pheny1)-i'urylmethane;

Bis(2 hydroxy 5 t-butylphenyl) -5-methylfu rylmethane;

Bis(2 hydroxy 3 t-amylphenyl) -5-methylturylmethane;

Bis(2 hydroxy 3,5-di-t-octylphenyl) -5-methylfurylmethane;

Bis(2 hydroxy-5-t-butyl-3-sec-butylphenyl) -5- methylfurylmethane;

Bis(2 hydroxy-3-isopropyl-S-t-butylphenyl) -5- methylfurylmethane;

Bis(2 hydroxy-5-isopropyl-3-t-amylphenyl) -5'- methylfurylmethane;

Bis(2 hydroxy 3 ethyl 5-t-octy1phenyD-5- methylfurylmethane;

Bis(2 methyl 4 hydroxy-5t-butylphenyl) -5- methylfurylmethane;

Bis(2 hydroxy 3 methyl-5-t-amylphenyl) -5- methylfurylmethane;

Bis(2 hydroxy 3 t-octyl-5-methylphenyl) -5- methylfurylmethane; and the like. The compounds of the type herein disclosed in -furyladdition to stabilizin gasolines are also useful in retarding the oxidation of other petroleum oils, such as lubricating oils, turbine oils, transformer oils, and the like, as well as animal and vegetable about 4 We have found that the addition 01 from 0.005 to about 2 per cent by weight of the compounds of the type herein disclosed to an oil normally tending to undergo oxidational changes will substantially inhibit or greatly retard the formation of compounds which are corrosive to metal in lubricating oils, and will increase the oxygen and gum stability of gasolines and other motor fuels. The exact amount of antioxidant used in any particular case will depend upon the nature 01' the base oil as well as the severity oi the conditions to which it is subjected, in any case the amount being suflicient to inhibit the oxidation of said base oils.

The finished lubricating oil may also contain other additive agents including oiliness and extreme pressure agents, such as aromatic chlorine-containing compounds, stabilized chlorinated paraiiins, sulfurized fatty oils and high molecular weight ketones and esters; viscosity index improvers, such as high molecular weight polymers of isobutylene and the polymers of methacrylic esters; pour point depressants, such as a condensation product of chlorinated wax and naphthalene and a condensation product of chlorinated wax and phenol followed by further condensation of this reaction product with organic acids: detergents, such as nickel naphthenate, metal salts of ethylhexyl salicylate, and metal salts of alkyl substituted phenol sulfides; foam inhibitors, such as organo-silicon oxide condensation products, and organo-silicol condensation products: and other oxidation inhibitors, such as alkylated phenols, if desired.

The compounds of the type disclosed herein may be prepared by condensing a tertiary alkyl oils.

phenol with a 'iurfural as represented by the fol-' lowing reaction using HIC- cm mc-c-cm mo- -cm m on. bin The molecular ratio of the alkyl phenol to the H o 2 +oimoono iurfural may vary depending upon the number" of reactive positions capable of substitution on the aromatic nucleus of the particular phenol employed and upon the final product desired. but in accordance with our invention, is advantaeously maintained at about 2:1. In carrying out the reaction, it is generally desirable to maintain the reactants under an inert atmosphere. We introduce the alkyl phenol and the furfural into a reaction vessel containing a previously prepared basic catalyst. The reaction temperature is maintained at about C. and the reaction is allowed to proceed until no more solid appears to be formed. The solid product is then separated from the reaction mass, washed with water until neutral and then purified by recrystallization from a suitable solvent.

As examples of the alkyl phenols which may be octylphenol;

8 tert-butyl-Z-sec-butylphenol; 2-isopropyl-4-tertbutylphenol; 2-isopropyl-4-tert-amylphenol; 2- isopropyl 4 tert octylphenol; 2 ethyl-4-tertbutylphenol; 2 ethyl 4 tert amylphenol; 2- ethyl-4-tert-octylphenol; 4-ethyl 2 tert-butylphenol; 4-ethyl-2-tert-amylphenol; -4-ethyl-2- tert-octylphenol; 2-methyl 4 tert-butylphenol; 2-methyl 4 tert-amylphenol; 2-methyl-4-tertoctylphenol; 3-methy1- 6 tert-butylphenol; 3- methyl-fi-tert-amylphenol; 3 methyl 6 tertocwlphenol; I methyl-Z-tert-amylphenol; 4 methyl 2 tert- 2,3 di-methyl-G-tert-butylphenol; l-tert-butyl-Z-naphthol; 4-tert-butyl 1 naphthol, and the like.

The furfural compounds which may be used in accordance with our invention include furfural and alkyl substituted furiurals. By "alkyl substituted furfura we mean furtural compounds wherein one or more of the 3, 4 or 5 positions are occupied by a primary, secondary or tertiary alkyl group such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-amyl, tert-amyl, and the like. As examples of some of the i'urfurals which may be used in accordance with our invention, may be mentioned furfural,

3-methyl-furiural, 4-methyl-furfural, 5-methyl-- furfural, 3-ethyl-furfural, 4-ethyl-furfural, 5-

ethyl-furfural, 4-isopropyi-iurfural, 5-isopropyli'urfural, 4-tert-butyl-furfural, B-tert-butyl-iurrural, S-anwl-furfural, 5-benzyl-furfural, 3,4-dimethyl-furfural, 3,5-dimethyl-furfural, 4,5-dimethyl-furfural, trimethyl-furfural, and the like. Dihydrofurfur'al and tetrahydrofurfural may also be used.

As condensation catalysts, we advantageously employ basic catalysts such as metal alkoxides (sodium ethoxide) ethanolamine, diethanolamine, pyridine, piperidine, quinoline, and the like. The amount of the condensing agent required may be as little as 1 per cent based on the total weight of the reactants. However, larger amounts may also be used when desired.

The condensation reaction is carried out preferably at a temperature below about 150 C.

In the following specific example, there is illustrated the preparation of bis(2-hydroxy-3-tbutyl 5 methylphenyl) furylmethane and its effectiveness in inhibiting oxidational changes in a motor fuel. The oxidation stability test employed in showing the efiectiveness of, this compound is known as the A. S. T. M. Standard Test, D525-46 (Committee D-2).

Into a flask provided with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube and also containing a previously prepared sodium ethoxide catalyst were placed 24 grams (0.25 mole) for furfural and 82.1 grams (0.5 mole) of o-tertiary-butyl-paracresol.' A nitrogen inlet tube was provided in order to maintain an inert atmosphere during the preparation of the catalyst as well as during the condensation reaction. The sodium ethoxide catalyst was prepared by warming 0.68 gram of finely cut sodium in dry benzene with an excess of absolute ethanol. After reaction was complete as evidenced by the 4-methyl- 2 tert-butylphenol; 4-

disappearance of the sodium, the benzene and excess ethanol were evaporated under reduced pressure. The solid residue thus obtained was then placed under a hours to remove any remaining ethanol. To the sodium ethoxide catalyst thus obtained were added the furfural and o-tertiary-butyl-paracresol in the proportion as above-described.

pressure of 15 mm. of mercury and heated at about 110 to 120 C. for two The reaction mass thus formed was maintained under a nitrogen atmosphere and stirred continuously for five hours at a temperature of about 98 to 100 C. A viscous product was obtained. This product was dissolved in 500 m1. of hexane. and washed with water until neutral. The organic phase was then treated with per cent aqueous alcohol to remove any unreacted orthotertiary-butyl-paracresol. The hexane was then removed under vacuum in a desiccator. A solid product consisting essentially of bis(2-hydroxy- 3-t-butyl 5 methylphenyl) iurylmethane was thus obtained.

The ultimate analysis of the product as above obtained compared with the theoretical composition was as follows: V, V

The bis(Z-hydroxy-3-t-butyl-5-methylphenyl)- furylmethane thus obtained is insoluble in water and in dilute aqueous alkali solutions and is soluble in various organic solvents such as alcohol. acetone, ether, ligroin, gasoline, lubricating oils and other petroleum products.

When the product obtained as above described was added to a reference gasoline having an induction period of 2.6 hours under the conditions of the above mentioned A. S. T. M. test, in the proportion of 0.0002 mole per ml. of gasoline (0.081 gram per 100 ml.), the induction period increased to 4.50 hours.

While our invention has been described above with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such illustrated examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

We claim:

1. A compound represented by the structural formula:

on on an t wherein R is selected from the class consisting of furyl and alkyl substituted turyl groups, R1 is a tertiary alkyl radical containing at least 4 carbon atoms, and R2 is a member of'the group consisting of hydrogen and alkyl radicals containing no more than 8 carbon atoms.

2. A compound represented by the structural formula:

Rg R1' R2 BI wherein R. is selected from the class consisting of furyl and alkyl substituted iuryl groups. R1 is a tertiary butyl radical, and R: is a member of the group consisting of hydrogen and alkyl radicals containing no more than 8 carbon atoms.

containing no more than 3. A compound represented by the structural formula :1: Q g! Q 'Rr Rl RI wherein R is selected from the class consisting of furyl and alkyl substituted furyl groups, R1 is a tertiary amyl radical, and R2 is a member of the group consisting of hydrogen and alkyl radicals containing no more than 8 carbon atoms.

4. A compound represented by the structural formula:

H Q E E; R: R1 R1 wherein R is selected from the class consisting of furyl and alkyl substituted furyl groups, R1 is a tertiaryroctyl radical, and R2 is a member of the group consisting of hydrogen and alkyl radicals 8 carbon atoms.

5. A compound represented by the structural formula:

OH OH wherein R is selected from the class consisting of furyl and alkyl substituted furyl groups, R1 is a tertiary butyl radical, and R2 is hydrogen.

6. A compound represented by the structural formula:

v G i) R: R1 R: R: wherein R is selected from the class consisting of furyl and alkyl substituted fury] groups, R1 is a tertiary butyl radical, and R2 is a methyl radical.

V 7. Bis(2-hydroxy-5-t-butylphenyl) =furylmethane.

8. Bis(2 hydroxy-3-t-butyl-5-methylphenyl) furylmethane.

9. A new composition of matter comprising a major proportion of an oil normally tending to undergo deterioration and a, small amount, suflicient to inhibit such deterioration, of a compound represented by the structural formula:

R, R; R: i R:

wherein R is selected from the class consisting of iuryl and alkyl substituted furyl groups, R1 is a :ertiary alkyl radical containing at least 4 carbon ltoms, and R2 is a member of the group consistng of hydrogen and alkyl radicals containing more than 8 carbon atoms.

10. A new composition of matter comprising L major proportion of an oil normally tending to undergo deterioration and a small amount, sumcient to inhibit such deterioration, of a compound represented by the structural iormula:

an R R B wherein R is selected from the class consistingof furyl and'alkylsubstituted furyl groups, R1 is a tertiary butyl radical, and R: is a member of the group consisting of hydrogen and alkyl radicals containing no more than 8 carbon atoms.

11. A new composition of matter comprising a major proportion of an oil normally tending to undergo deterioration and a small amount, sum-'- cient to inhibit such deterioration, of a compound represented by the structural formula:

as i

as R R B wherein R is selected from the class consisting of furyl and alkyl substituted furyl groups, R1 is a tertiary alkyl radical containing at least 4 carbon atoms, and R: is a member or the group consisting of hydro en and alkyl radicals containing no more than 8 carbon atoms.

13. A motor fuel comprising a hydrocarbon oil boiling within a gasoline boiling-point range normally tending to undergo oxidational changes and a small amount, sufllcient to inhibit such oxidational changes, of a compound represented by the structural formula:

on on R: R1 R: R!

wherein R is selected from the class consisting of fury] and alkyl substituted furyl groups, R1 is a tertiary butyl radical, and R2 is a member of the group consisting of hydrogen and alkyl radicals containing no more than 8 carbon atoms.

14. A motor fuel comprising a hydrocarbon oil boiling within a gasoline boiling-point range normally tending to undergo oxidational changes and a small amount, suilicient to inhibit such 0x1- dational changes, of a compound represented by the structural formula:

R: R1 R1 R1 wherein R is selected from the class consisting of furyl and alkyl substituted furyl groups, R1 is a tertiary butyl radical, and R2 is hydrogen.

15. A motor fuel comprising a hydrocarbon oil boiling within a gasoline boiling-point range normally tending to undergo oxidational changes and a small amount, suflicient to inhibit such oxidational changes, of a compound represented by the structural formula:

' as l wherein R is selected from the class consisting of iuryl and alkyl substituted furyl groups, R1 is a tertiary butyl radical, and R2 is a methyl radical.

16. A motor fuel comprising a hydrocarbon oil boiling within a gasoline boiling-point range normally tending to undergo oxidational changes and small amount, sufllcient to inhibit such oxidational changes, or bis(2-hydroxy-5-t-butylphenyl) -furylmethane.

17. A motor fuel comprising a hydrocarbon oil boiling within a gasoline boiling-point range normally tending to undergo oxidational changes and a small amount, suflicient to inhibit such oxidational changes, of bis(2-hydroxy-3-t-butyl- -methylphenyl) Jurylmethane.

18. A lubricant comprising a lubricating oil susceptible to deterioration and a small amount sufllcient to inhibit such deterioration, of a compound represented b the structural formula:

R, R; R! R1 wherein R is selected from the class consisting of V furyl and alkyl substituted furylgroups, R1 is a tertiary alkyl radical containing at least 4 car- REFERENCES CITED The following references are of record'in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,140,052 Hiemenz et a1 Dec. 13, 1938 2,321,311 Mottlau June 8, 1943 2,330,722 Lieber Sept. 28, 1943 2,362,516 Wasson et al Nov. 14, 1944 

1. A COMPOUND REPRESENTED BY THE STRUCTURAL FORMULA: 